Shape Primitives

Introduction

While mesh objects are incredibly versatile, the amount of computation required for performing collision detection between the tool and the object can become substantial when the number of polygons becomes large. To address this problem CHAI3D offers a selection of primitives that can be used to model simple shapes such as spheres, cylinders, boxes, etc... Instead of computing collisions with large sets of triangles, implicit models are used to quickly compute if a tool is located inside or outside of the shape. By combining these models with haptic effects we can substantially reduce the amount of computation necessary to compute interactive force between the haptic device and the environment.

Shape primitives.

Box Object

The following example illustrates how to create a box object and assign a surface haptic effect.

using namespace chai3d;

// create a box and define its dimensions
object = new cShapeBox(0.1, 0.2, 0.3)

// add object to world
world->addChild(object);

// set haptic properties
object->m_material->setStiffness(500);

// create a haptic surface effect
object->createEffectSurface();

Sphere Object

The following example illustrates how to create a sphere object and assign a surface haptic effect.

using namespace chai3d;

// create a sphere and define its radius
object = new cShapeSphere(0.3);

// add object to world
world->addChild(object);

// set haptic properties
object->m_material->setStiffness(500);

// create a haptic surface effect
object->createEffectSurface();

Cylinder Object

The following example illustrates how to create a cylinder object and assign a surface haptic effect.

using namespace chai3d;

// create a cylinder by defining its bottom and top radius, and its height
object = new cShapeCylinder(0.1, 0.1, 0.3)

// add object to world
world->addChild(object);

// set haptic properties
object->m_material->setStiffness(500);

// create a haptic surface effect
object->createEffectSurface();

Torus Object

The following example illustrates how to create a torus object and assign a surface haptic effect.

using namespace chai3d;

// create a torus
object = new cShapeTorus(0.25, 0.50);

// add object to world
world->addChild(object);

// set haptic properties
object->m_material->setStiffness(500);

// create a haptic surface effect
object->createEffectSurface();

Line Object

The following example illustrates how to create a line object and assign a magnetic haptic effect.

using namespace chai3d;

// create a line
line = new cShapeLine(cVector3d(0.0, 0.0, 0.0), cVector3d(1.0, 1.0, 1.0));
world->addChild(line);

// set color at each point
line->m_colorPointA.setWhite();
line->m_colorPointB.setWhite();

// create haptic effect and set haptic properties
line->createEffectMagnetic();
line->m_material->setMagnetMaxDistance(0.05);
line->m_material->setMagnetMaxForce(5.0);
line->m_material->setStiffness(500);